Two-beam semiconductor laser apparatus

ABSTRACT

A two-beam semiconductor laser device  10  includes: a two-beam semiconductor element LDC having a first and a second semiconductor laser elements LD 1  and LD 2  that can be driven independently and that are formed integrally on a substrate; and a submount  63  having, mounted on a front part thereof, the two-beam semiconductor laser element LDC with the light-emitting face thereof directed forward and having a first and a second electrode pads  64  and  65  connected to electrodes  61  and  62  of the first and second semiconductor laser element LD 1  and LD 2  by being kept in contact therewith. The first and second electrode pads  64  and  65  are formed to extend farther behind the two-beam semiconductor laser element LDC, and wires  14  and  16  are wire-bonded behind the two-beam semiconductor laser element LDC.

TECHNICAL FIELD

The present invention relates to a two-beam semiconductor laser device,and more particularly to a single-mode two-beam semiconductor laserdevice that employs a package composed of a frame and a resin member andthat can emit laser light of two wavelengths individually.

BACKGROUND ART

As optical recording media, there have been known, among others, compactdiscs (CDs), recordable compact discs (CD-Rs), rewritable compact discs(CD-RWs), and as those offering higher recording densities, digitalversatile discs (DVDs) and recordable DVDs. To record and play back,among these recording media, at least DVDs, CDs, CD-Rs, and CD-RWs, itis necessary to use, as the light source for optical pickups, onecapable of emitting laser light of wavelengths 650 nm and 780 nm.

The laser light of a wavelength of 650 nm is for playback of DVDs, andthe laser light of a wavelength of 780 nm is for playback of CDs and forrecording and playback of CD-Rs and CD-RWs. The laser light of awavelength of 650 nm may be used for recording of recordable DVDs. Onthe other hand, the recent demands for faster recording have beenrequiring higher-output light sources.

As a light source for incorporation in an optical pickup, there has beenknown a two-beam semiconductor laser device that can emit a laser lightof wavelengths 650 nm and 780 nm from a single package. By incorporatinga two-beam semiconductor laser device into an optical pickup, it ispossible to make the optical pickup compact and to simplify the assemblythereof.

FIG. 6 and FIG. 7 are a front view and a perspective view respectively,showing a substantial part of a conventional two-beam semiconductorlaser device. The two-beam semiconductor laser device 50 has a two-beamsemiconductor laser element LDC mounted on a submount 63. The two-beamlaser element LDC is integrated on a single substrate 51, with a firstsemiconductor laser element LD1 and a second semiconductor laser elementLD2 formed separately from each other.

The substrate 51 is formed of, for example, n-type GaAs. The firstsemiconductor laser element LD1 is formed of, for example, an AlGaInPsemiconductor, and outputs laser light of a wavelength of 650 nm. Thesecond semiconductor laser element LD2 is formed of, for example, anAlGaAs semiconductor and outputs a laser light of a wavelength of 780nm. The specific details of the structures of the first, AlGaInP,semiconductor laser element LD1 and the second, AlGaAs, semiconductorlaser element LD2 are disclosed in Patent Publications 1 and 2, andtherefore, in this respect, only a brief description thereof will begiven below.

The first, AlGaInP, semiconductor laser element LD1 has an n-typeAlGaInP semiconductor layer 52 formed on the n-type GaAs substrate 51.On the n-type AlGaInP semiconductor layer 52, a p-type AlGaInPsemiconductor layer 53 is formed with a first junction layer 54 laid inbetween. The first junction layer 54 contains a single-quantum-well(SQW) or multiple-quantum-well (MQW) structure, and has part thereofformed into a first light-emitting portion 55.

Likewise, the second, AlGaAs, semiconductor laser element LD2 has ann-type AlGaAs semiconductor layer 56 formed on the n-type GaAs substrate51. On the n-type AlGaAs semiconductor layer 56, a p-type AlGaAssemiconductor layer 57 is formed with a second junction layer 58 laid inbetween. The second junction layer 58 contains the same structure as thefirst junction layer 54, and has part thereof formed into a secondlight-emitting portion 59.

On the back face of the substrate 51, an n-side common electrode 60 isformed. On the top face of the first semiconductor laser element LD1, afirst p-side electrode 61 is formed. On the top face of the secondsemiconductor laser element LD2, a second p-side electrode 62 is formed.

On the face of the submount 63 to which the two-beam semiconductor laserelement LDC is fixed, a first electrode pad 64 and a second electrodepad 65 are formed separate from each other by patterning. The first andsecond p-side electrodes 61 and 62 of the two-beam semiconductor laserelement LDC are fixed to the first and second electrode pads 64 and 65,respectively. This configuration enables the first and secondsemiconductor laser elements LD1 and LD2 to be driven individually.

The two-beam semiconductor laser element LDC has a so-calledjunction-down structure; that is, it has the first and second junctionlayers 54 and 58 located close to the submount 63. This enables thefirst semiconductor laser element LD1 and the second semiconductor laserelement LD2 to dissipate heat efficiently. Thus, the submount 63 servesas a heatsink, and thereby helps stabilize the operation of and increasethe output of the two-beam semiconductor laser element LDC.

Behind the two-beam semiconductor laser element LDC on the submount 63,a photodetector 66 such as a photodiode is fitted. According to what isdetected by the photodetector 66, the light emission output of thetwo-beam semiconductor laser element LDC is controlled.

The submount 63, on which the two-beam semiconductor laser element LDCis fixed, is fixed to a heatsink plate or a leadframe (not shown), andto the n-side common electrode 60 of the two-beam semiconductor laserelement LDC, a wire 67 is connected at one end thereof. One end of awire 68 and one end of a wire 69 are connected to the first electrodepad 64 and the second electrode pad 65, respectively. One end of a wire70 is connected to the photodetector 66. The other ends of the wires 67to 70 are connected to lead terminals (not shown). In this way, thetwo-beam semiconductor laser device 50 is fabricated.

In the two-beam semiconductor laser device 50 structured as describedabove, the first semiconductor laser element LD1 can be drivenindependently by passing a current between the first p-side electrode 61and the n-side common electrode 60; the second semiconductor laserelement LD2 can be driven independently by passing a current between thesecond p-side electrode 62 and the n-side common electrode 60. Thus bydriving the first semiconductor laser element LD1, laser light ofwavelength of 650 nm can be produced, and by driving the secondsemiconductor laser element LD2, laser light of wavelength of 780 nm canbe produced.

Known semiconductor laser devices typically use can packages or framepackages. In a semiconductor laser device using a can package, leads arefitted one-by-one to a metal stem, and a laser element is mounted on themetal stem and is sealed with a cap. In a semiconductor laser deviceusing a frame package, a semiconductor laser element is mounted on ametal frame, and these are then insert-molded. Semiconductor laserdevices using frame packages have been attracting attention for theirlow cost and good mass productivity.

Compared with conventionally widely used semiconductor laser devicesusing can packages, however, semiconductor laser devices using framepackages offer poorer heat dissipation. For this reason, semiconductorlaser devices using frame packages are now mostly used for infraredlaser devices. Further improvements are required so as to makesemiconductor laser devices using frame packages usable as high-outputlaser devices for use with CD-Rs and CD-RWs, red laser devices for usewith DVDs, two-wavelength laser devices, or blue laser devices operatingat high operating voltages.

Patent Publication 3 discloses a semiconductor laser device using aframe package in which such an improvement has been made. FIG. 8 andFIG. 9 are a perspective view and a front view, respectively, of thistype of semiconductor laser device using a frame package. FIG. 10 is asectional view taken along line X-X′ shown in FIG. 9.

In the semiconductor laser device 80, a submount 83 is arranged in afixed position on the top face of a frame 82. A semiconductor laserelement 84 is arranged in a fixed position on the top face of thesubmount 83. The frame 82 is formed of a metal having good thermal andelectrical conductivity, such as copper, iron, or an alloy of either,and is formed into a plate. The frame 82 includes a main frame 86 onwhich the semiconductor laser element 84 is mounted and sub frames 87and 88 for wiring that are independent of the main frame 86. The mainframe 86 and the sub frames 87 and 88 are integrated into a framepackage by being molded in a resin-molded member 85 that is electricallyinsulative.

The main frame 86 includes an element mount portion 86 a, a lead portion86 b and wing portions 86 c and 86 d. On the element mount portion 86 a,the submount 83 is mounted. The lead portion 86 b serves as a currentpath. The wings 86 c and 86 d are formed to project to the left andright, respectively, for the purpose of heat dissipation andpositioning. In the main frame 86, a thick-walled section 86 e and athin-walled section 86 f are formed. The thick-walled section 86 e isformed by thickening a front part of the element mount portion 86 a andfront parts of the wing portions 86 c and 86 d. The thin-walled section86 f is formed by thinning the lead portion 86 b and rear parts of thewing portions 86 c and 86 d.

The sub frames 87 and 88 are formed to be thin-walled like the leadportion 86 b. This enables the lead portion 86 b and the sub frames 87and 88 to be finely processed with ease when the frame 82 is punched outby pressing. Therefore, it is possible to make the semiconductor laserdevice 80 compact by keeping the intervals between the lead portion 86 band the sub frames 87 and 88 short.

The resin-molded member 85 is formed by insert molding in such a mannerthat it sandwiches the frame 82, from above the front face and below theback face of the frame 82. On the front face of the resin-molded member85 is formed a laser output window 85 a through which laser light isemitted, as well as an enclosure 85 b that is U-shaped so as to be openfrontward. Taper faces 85 c are formed in front-end parts of left andright side portions of the enclosure 85 b. The taper faces 85 c permitthe semiconductor laser device 80 to be inserted smoothly to be arrangedin a predetermined position. The back face of the resin-molded member 85is formed to be a flat surface 85 d that covers the element mountportion 86 a, and has substantially the same outer shape (hexagonalshape) as the enclosure 85 b located on the front face of theresin-molded member 85.

The resin-molded member 85 does not cover the part of the element mountportion 86 a of the main frame 86 in the enclosure 85 b, nor does itcover the sub frames 87 and 88. Thus, in these locations, the surfacesof the main frame 86 and the sub frames 87 and 88 are exposed. On theexposed part of the element mount portion 86 a, the semiconductor laserelement 84 is arranged and fixed, with the submount 83 placed inbetween. Subsequently, the semiconductor laser element 84 is connectedto the main frame 86 with a wire (not shown), and the submount 83 isconnected to the sub frames 87 and 88 with wires (not shown).

The submount 83 is built as a light receiving element whose basematerial is Si. This makes it possible to monitor the light emitted fromthe rear face of the semiconductor laser element 84. Instead of Si, aceramic or metal material that has high thermal conductivity may beused, such as AlN, SiC, or Cu. The submount 83 is fixed to the elementmount portion 86 a, for example, with a solder material such as Pb—Sn,Au—Sn, or Sn—Bi, or with Ag paste. The semiconductor laser element 84 isfixed to the submount 83, in a predetermined position thereon, forexample, with a solder material such as Au—Sn or Pb—Sn, or with Agpaste.

Structured as described above, the semiconductor laser device 80 using aframe package offers the following advantages: since the surface of thesemiconductor laser element 84 is exposed, it offers good heatdissipation; it has a simple structure, and is therefore suitable formass production.

Patent Publication 1: JP-A-H11-186651 (Claims, paragraphs [0017] to[0023], FIG. 1)Patent Publication 2: JP-A-2002-329934 (Claims, FIG. 1, FIG. 4) PatentPublication 3: JP-A-2002-43679 (paragraphs [0010] to [0022], FIG. 1,FIG.2, FIG. 4)

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

A semiconductor laser device is usually operated in single mode. In acase where a semiconductor laser device is used in an optical pickup forrecording and playing back optical discs, however, it needs to beoperated in multiple mode for playback to cope with return light fromthe optical disc. For this purpose, multiple mode is emulated byhigh-frequency modulation, and, when this is done, the semiconductorlaser device needs to be matched with the high-frequency modulation.

Disadvantageously, the conventional semiconductor laser device 80 usinga frame package disclosed in Patent Publication 3 has, for better heatdissipation and easy wire bonding, the submount 83 formed far largerthan the semiconductor laser element 84. Moreover, the lead portion 85 band the sub frames 87 and 88 are located far from the submount 83 andthe semiconductor laser element 84. Thus, longer wires are needed thanin a semiconductor laser device using a metal can package.

When a semiconductor laser device is operated by high-frequencymodulation, since the wires have varying inductances according to thelength thereof, the wires need to be made as short as possible. Thus,inconveniently, the semiconductor laser device 80 cannot be stablyoperated by high-frequency modulation.

This inconvenience is experienced even with a two-beam semiconductorlaser device if it uses a frame package. In addition, as shown in FIG. 7described above, the two-beam semiconductor laser device 50 has thephotodetector 66 arranged behind the two-beam semiconductor laserelement LDC, and thus has four terminals. This requires even longerwires to be used as the wires 67 to 69 bonded to the n-side commonelectrode 60 and the first and second electrode pads 64 and 65, and thusinconveniently causes the inductances thereof to vary unduly greatly.

Furthermore, the presence of the photodetector 66 makes it difficult tominiaturize the two-beam semiconductor laser device 50. Moreover, sincethe space behind the two-beam semiconductor laser element LDC isoccupied by the photodetector 66, the wires 68 and 69 are connected tothe first and second electrode pads 64 and 65 at the sides of thetwo-beam semiconductor laser element LDC. This makes the submount 63unduly wide, which makes it more difficult to miniaturize the two-beamsemiconductor laser device 50.

Incidentally, whereas conventional semiconductor laser elements areabout 300 to 400 μm long, recent higher-output semiconductor laserelements are about 1 to 1.5 mm long, that is, they are three to fivetimes longer than conventional ones. This makes the submount 63 is evenlarger. Under these circumstances, there is a need for a structure of atwo-beam semiconductor laser device in which a two-beam semiconductorlaser device can be made compact.

In search of a solution to the inconveniences experienced in thefabrication of a two-beam semiconductor laser device made particularlycompact with a frame package as described above, the inventors of thepresent invention have conducted various studies, which have led to thepresent invention.

An object of the present invention is to provide a single-mode two-beamsemiconductor laser device that permits size reduction and that can bestably operated in multiple mode.

Means for Solving the Problem

To achieve the above object, according to the present invention, atwo-beam semiconductor laser device is provided with: a two-beamsemiconductor element having a first and a second semiconductor laserelements that can be driven independently and that are formed integrallyon a substrate; and a submount having, mounted on a front part thereof,the two-beam semiconductor laser element with a light-emitting facethereof directed forward and having a first and a second electrode padsconnected to electrodes of the first and second semiconductor laserelement by being kept in contact therewith. Here, the first and secondelectrode pads are formed to extend farther behind the two-beamsemiconductor laser element and are wire-bonded behind the two-beamsemiconductor laser element.

According to the present invention, in the two-beam semiconductor laserdevice structured as described above, the first and second electrodepads are wire-bonded at the rear end of the submount.

According to the present invention, in the two-beam semiconductor laserdevice structured as described above, the distance from the rear end ofthe two-beam semiconductor laser element to the position where the firstand second electrode pads are wire-bonded is 300 μm or shorter.Theoretically, it is preferable that the lower limit value of thedistance from the rear end of the two-beam semiconductor laser elementto the position where the first and second electrode pads arewire-bonded be as small as possible. However, if the distance is toosmall, wire bonding cannot be carried out easily. Thus, the distanceshould be determined properly, taking into consideration the diameter ofthe wire and the size of the jig for wire bonding. The wire can be madeshort enough even if the distance is over 300 μm. However, in such acase, the size of the submount is disadvantageously large, and thus theupper limit value of the distance should be 300 μm.

According to the present invention, in the two-beam semiconductor laserdevice structured as described above, the lateral length of the submountis 400 μm or more but 700 μm or less. If the lateral length of thesubmount is less than 400 μm, wire bonding cannot be carried out easilyand a short circuit is liable to occur between the two electrode padsdisposed on the submount. On the other hand, if the lateral length ofthe submount is over 700 μm, there is no longer any advantage from theview point of miniaturization of the two-beam semiconductor laserdevice, and for this reason, the upper limit value of the lateral lengthof the submount should be 700 μm.

According to the present invention, in the two-beam semiconductor laserdevice structured as described above, the submount is mounted in apackage composed of a frame and a resin member.

According to the present invention, the two-beam semiconductor laserdevice structured as described above is built as a three-terminaltwo-beam semiconductor laser device having three terminals.

Advantages of the Invention

According to the present invention, the first and second electrode padsare formed to extend farther behind the two-beam semiconductor laserelement, and are wire-bonded behind the two-beam semiconductor laserelement. This helps reduce the lateral length of the submount, and thushelps make the two-beam semiconductor device compact. In addition, sincethe position where the wire bonding is performed is farther behind, thewires used here can be made shorter than conventionally needed. Thispermits the inductances of the wires to be made lower by about 20% thanis conventionally usual. Thus, the two-beam semiconductor laser devicecan be stably operated in multiple mode emulated by high-frequencymodulation.

According to the present invention, since the first and second electrodepads are wire-bonded at the rear end of the submount, no photodetectoris arranged behind the submount, and thus the wires can be made evenshorter to permit the two-beam semiconductor laser device to be stablyoperated in multiple mode emulated by high-frequency modulation.

According to the present invention, the distance from the rear end ofthe two-beam semiconductor laser element to the position where the firstand second electrode pads are wire-bonded is 300 μm or less, and thishelps make the submount compact. Thus, the two-beam semiconductor laserelement is arranged close to the rear end of the submount 63, and thishelps reduce the lengths of the wires that are connected to the two-beamsemiconductor laser element. Thus, the two-beam semiconductor laserdevice can be stably operated in multiple mode emulated byhigh-frequency modulation.

According to the present invention, since the lateral length of thesubmount is 400 μm or more but 700 μm or less, the two-beamsemiconductor laser device can be made compact, and wire-bonding can becarried out easily.

According to the present invention, the submount is mounted in a packagecomposed of a frame and a resin member, and this permits the two-beamsemiconductor laser device to be compact, inexpensive, and suitable formass production.

According to the present invention, the two-beam semiconductor laserdevice is built as a three-terminal two-beam semiconductor laser device,and this helps make the two-beam semiconductor laser device more compactas much more as the number of terminals is reduced, than isconventionally usual.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A perspective view showing a two-beam semiconductor laser elementof a two-beam semiconductor laser device embodying the presentinvention.

FIG. 2 A plan view showing a two-beam semiconductor laser element of atwo-beam semiconductor laser device embodying the present invention.

FIG. 3 A perspective view showing a two-beam semiconductor laser deviceembodying the present invention.

FIG. 4 A plan view showing a two-beam semiconductor laser deviceembodying the present invention.

FIG. 5 A sectional view taken along line X-X′ shown in FIG. 4.

FIG. 6 A front view showing a conventional two-beam semiconductor laserelement.

FIG. 7 A perspective view showing a conventional two-beam semiconductorlaser element.

FIG. 8 A perspective view showing a conventional two-beam semiconductorlaser device.

FIG. 9 A plan view of the semiconductor laser device shown in FIG. 8.

FIG. 10 A sectional view taken along line X-X′ shown in FIG. 9.

LIST OF REFERENCE SYMBOLS

10, 50 two-beam semiconductor laser device

12, 14, 16, 67, 68, 69 wire

22, 82 frame

23, 85 resin-molded member

24, 86 main frame

24 a, 86 a element mount portion

25, 26, 87, 88 sub frame

27, 85 a laser output window

28, 85 b enclosure

29, 29′ end part

55 first light-emitting portion

59 second light-emitting portion

60 n-side common electrode

61 first p-side electrode

62 second p-side electrode

63 submount

first electrode pad

65 second electrode pad

66 photodetector

80 semiconductor laser device

LDC two-beam semiconductor laser element

LD1 first semiconductor laser element

LD2 second semiconductor laser element

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of how the present invention is carried out will bedescribed below with reference to the accompanying drawings. It shouldbe understood, however, that the embodiment presented below is simplyintended to give an example of a two-beam semiconductor laser devicethat embodies the technical idea of the present invention, and thereforethe two-beam semiconductor laser device specifically described below isnot intended to limit in any way the manner in which to carry out thepresent invention. That is, the present invention finds wide applicationin the technical fields to which the appended claims are directed.

FIG. 1 and FIG. 2 are a perspective view and a plan view, respectively,showing a substantial part of a two-beam semiconductor laser deviceembodying the present invention. For the sake of ease of description,such portions as find their counterparts in FIG. 6 and FIG. 7 describedabove are identified with common reference numerals, and overlappingdescriptions will not be repeated. The two-beam semiconductor laserelement LDC has a junction-down structure where a junction portion thatincludes a first and a second light-emitting portions 55 and 59 is fixedclose to a submount 63.

A first semiconductor laser element LD 1 that emits laser light of awavelength of 650 nm for recordable DVDs is arranged on the left side asseen from the front in FIG. 1. A second semiconductor laser element LD2that emits laser light of a wavelength of 780 nm for CDs/CD-Rs is placedon the right side as seen from the front in FIG. 1. Between the firstand second semiconductor laser elements LD1 and LD2 is formed a grooveto separate them from each other.

The submount 63 is formed of a ceramic or metal material that has highthermal conductivity, such as AlN, SiC, Cu, or Si. On the top face ofthe submount 63 are disposed a first and a second electrode pads 64 and65 that are formed by patterning of Ti—Pt—Au. A first p-side electrode61 (see FIG. 6) is disposed right under a first light-emitting portion(waveguide) 55 of the first semiconductor laser device LD1, and is fixedwith solder such as Au—Sn onto the first electrode pad 64.

Likewise, a second p-side electrode 62 (See FIG. 6) is disposed rightunder a second light-emitting portion (waveguide) 59 of the secondsemiconductor laser device LD2, and is fixed with solder such as Au—Snonto the second electrode pad 65. This enables the heat generated at thefirst and second semiconductor elements LD1 and LD2 to be efficientlyconducted to the submount 63 via the first and second electrode pads 64and 65, and then dissipated.

The two-beam semiconductor laser element LDC and the submount 63 areeach formed in the shape of a flat box that is elongate in the directionof the emission of laser light. The lateral length W of the submount 63is equal to or slightly larger than the lateral length of the two-beamsemiconductor laser element LDC.

The submount 63 is extended in the direction pointing away from themain-laser-light-emitting face of the two-beam semiconductor laserelement LDC. In this way, the two-beam semiconductor laser element LDCis arranged on a front part of the submount 63 with the light-emittingface of the former facing forward, and a rear part of the submount 63serves as an wire bonding area.

Incidentally, in the submount 63 of this embodiment, no photodetector 66for monitoring (see FIG. 7) as used in the conventional example isdisposed. In a high-output semiconductor laser element, to enhance theoutput of laser light, the face pointing away from thelaser-light-emitting direction is given a higher reflectivity. Thishelps reduce the amount of laser light emitted backward, and thuseliminates the need to bother to integrate the photodetector 66 into thesubmount 63. That is, the photodetector 66 may be omitted.

At the rear end of the submount 63, to the first and second electrodepads 64 and 65, one ends of wires 14 and 16 for electrically connectingthem to lead terminals (25 and 26, see FIG. 3) are wire-bonded. To ann-side common electrode 60 formed on the back face of the two-beamsemiconductor laser element LDC, one end of a wire 12 for electricallyconnecting the n-side common electrode to a lead terminal (24 b, seeFIG. 3) is wire-bonded.

The wires 14 and 16 are wire-bonded where the distance L from the rearend of the semiconductor laser element LDC is 300 μm or less. Theshorter the distance L is, the shorter the submount 63 can be made.Therefore, the two-beam semiconductor laser element LDC is disposedclose to the rear end of the submount 63, and thus the wire 12 can bemade short. The distance L may be determined properly taking intoconsideration the diameters of the wires 14 and 16 and the size of thejig for wire bonding such as an automatic bonder.

The lateral length W of the submount 63 may be determined taking intoconsideration the width of the first and second electrode pads 64 and65, and the distance between the first and second electrode pads 64 and65. The width of the first and second electrode pads 64 and 65 isproperly determined taking into consideration the diameters of the wires14 and 16 and the size of the jig for wire bonding such as an automaticbonder. The distance between the first and second electrode pads 64 and65 should be long enough to achieve electrical separation between them.This helps reduce the lateral length W of the submount 63 to as small asabout 400 μm in this embodiment. It is preferable that the laterallength W of the submount 63 be about 700 μm at most, though there is nospecific reason that this should be so.

FIG. 3 and FIG. 4 are a perspective view and a front view, respectively,of the two-beam semiconductor laser device of this embodiment. FIG. 5 isa sectional view taken along line X-X′ shown in FIG. 4. In the two-beamsemiconductor laser device 10, the two-beam semiconductor laser elementLDC and the submount 63 are mounted in a frame package composed of athree-terminal frame and a resin member.

In the two-beam semiconductor laser device 10, the submount 63 isarranged and fixed on the top face of a frame 22. On the top face of thesubmount 63, the two-beam semiconductor laser element LDC is arrangedand fixed.

The frame 22 is formed of a metal having good thermal and electricalconductivity, such as copper, iron, or an alloy of either, and is formedinto a plate. In addition, the frame 22 includes a main frame 24 onwhich the two-beam semiconductor laser element LDC is mounted and subframes 25 and 26 for wiring that are independent of the main frame 24.The main frame 24 and the sub frames 25 and 26 are integrated into aframe package by being molded in a resin-molded member 23 that iselectrically insulative.

The main frame 24 has an element mount portion 24 a, a lead portion 24b, and wings 24 c and 24 d. On the element mount portion 24 a, thesubmount 63 is mounted. The lead portion 24 b serves as a current path.The wings 24 c and 24 d are formed to project to the left and right,respectively, for the purpose of heat dissipation and positioning.

The lead portion 24 b and the sub frames 25 and 26 are formed to bethin-walled, and this enables them to be finely processed with ease whenthe frame 22 is punched out by pressing. Therefore, it is possible tomake the semiconductor laser device 10 compact by keeping the intervalsbetween the lead portion 24 b and the sub frames 25 and 26 short.

The resin-molded member 23 is formed by insert molding in such a mannerthat it sandwiches the frame 22, from above the front face and below theback face of the frame 22. On the front face of the resin-molded member23 is formed an enclosure 28 that has a laser output window 27 throughwhich laser light is emitted and that is U-shaped so as to be openfrontward. The front part of the enclosure 28 has a smaller width thanthe rear part thereof, and end parts 29 and 29′ disposed at the eitherend of the front part of the enclosure 28 extend parallel to the opticalaxis of the two-beam semiconductor laser element LDC. The end parts 29and 29′ with a smaller width in between than the rear part of theenclosure 28 permit the two-beam semiconductor laser device 10 to beinserted smoothly to be arranged in a predetermined position.

The back face of the resin-molded member 23 is so formed as to exposethe part of the back face of the main frame 24 facing the submount 63 soas to enclose that part. This helps enhance heat dissipation efficiency.

The resin-molded member 23 does not cover the part of the element mountportion 24 a of the main frame 24 in the enclosure 28, nor does it coverthe sub frames 25 and 26. Thus, in these locations, the surfaces of themain frame 24 and the sub frames 25 and 26 are exposed. On the exposedpart of the element mount portion 24 a, the semiconductor laser elementLDC is arranged and fixed, with the submount 63 placed in between.Subsequently the two-beam semiconductor laser element LDC is connectedto the lead portion 24 b with the wire 12, and the submount 63 isconnected to the sub frames 25 and 26 with the wires 14 and 16.Incidentally, the submount 63 is fixed to the frame 24, for example,with a solder material such as Pb—Sn, Au—Sn, or Sn—Bi, or with Ag paste.

In the above structured two-beam semiconductor laser device 10, thefirst and second electrode pads 64 and 65 are formed to extend fartherbehind the two-beam semiconductor laser element LDC and are wire-bondedbehind the two-beam semiconductor laser element LDC. This helps make thelateral length W of the submount 63 far smaller than in the conventionalexample shown in FIG. 7, and thereby to make the two-beam semiconductordevice compact.

Furthermore, since the position where the wire bonding is performed isfarther behind, the wire 14 used between the first electrode pad 64 andthe sub frame 26 and the wire 16 used between the second electrode pad65 and the sub frame 25 can be made shorter than conventionally needed.This permits the inductances of the wires 14 and 16 to be made lowerthan is conventionally usual. Thus, the two-beam semiconductor laserdevice 10 can be stably operated in multiple mode emulated byhigh-frequency modulation. Moreover, since no photodetector is arrangedbehind the submount 63, the first and second electrode pads 64 and 65are wire-bonded at the rear end of the submount 63. Thus, the wires 14and 16 can be made even shorter.

In addition, the position where wire bonding is performed is close tothe rear end part of the two-beam semiconductor laser element LDC. Thispermits the two-beam semiconductor laser element LDC to be disposedclose to the rear end of the submount 63, and thus helps shorten thelength of the wire 12 that connects the two-beam semiconductor laserelement LDC to the main frame 24. Thus, the two-beam semiconductor laserdevice can be more stably operated in multi mode emulated byhigh-frequency modulation.

The two-beam semiconductor laser device 10 fabricated according to thisembodiment is used as a three-terminal high-output two-wavelengthsemiconductor laser device. The size of the two-beam semiconductor laserdevice 10 is as follows: the width of the package at the front endthereof (the width of the enclosure 28 as measured at the end parts 29and 29′ in FIG. 3 and FIG. 4) is 2.7 mm, the-rear end width is 3.8 mm,and the length is 3.5 mm.

In contrast, it cannot be helped that a conventional high-outputtwo-wavelength semiconductor laser device, even if mounted in athree-terminal package without taking the photodetector intoconsideration, is large-sized to secure a space that accepts the laterallength of the submount and that permits assembly. Thus, the smallestdimensions possible are: the width of the package at the front endthereof is 3.8 mm, the rear end width is 3.8 mm, and the length is 3.5mm.

According to this embodiment, the wire bonding area at the side of thesubmount 63 can be ignored, and thus a compact package is realized thatis smaller both in the front end width and in the area by about 30% ascompared with conventional examples. In addition, it has been observedand confirmed that by making the wires 12, 14, and 16 shorter, theinductances of the wires can be made lower by about 20% than isconventionally usual.

INDUSTRIAL APPLICABILITY

The two-beam semiconductor laser device according to the presentinvention can be used for optical pickups that emit laser light of aplurality of wavelengths for recording or playback of DVDs, recordableDVDs, CDs, CD-Rs, or CD-RWs.

1-6. (canceled)
 7. A semiconductor laser device comprising: asemiconductor laser element emitting laser light; a frame on which thesemiconductor laser element is mounted; and a resin-molded portionarranged on the frame, around the semiconductor laser element, whereinthe resin-molded portion is arranged to both sides of an optical axis ofthe semiconductor laser element, and a width between outer surfaces ofmutually facing parts of the resin-molded portion as measured in a frontpart thereof is stepwise smaller than the width as measured in a rearpart thereof.
 8. The semiconductor laser device according to claim 7,wherein a width of a tip end of the frame is smaller than a width of theresin-molded portion as measured rearward of a front end thereof.
 9. Thesemiconductor laser device according to claim 7, wherein the frame isformed to extend sideways of the front part of the resin-molded portion.10. The semiconductor laser device according to claim 7, wherein theresin-molded portion has formed therein a laser output window open infront of the semiconductor laser element.
 11. The semiconductor laserdevice according to claim 7, wherein the front part of the resin-moldedportion extend parallel along both sides of the semiconductor laserelement.